I will be building soon (once the q9450 comes out) and I have a few questions regarding power supply placement.  I am going to buy the Lian Li A71b for a case.  The power supply can be placed in either a upper traditional location or at the bottem.  I am concerned about the heat of the power supply and other components as in heat going into the power supply or heat coming from the power supply affecting other components in the case.  What are your oppinions on the best location for the power supply?  Also power supplys are availible with the fan located on the top of the power supply and others with the fan on the bottem.  What do you think would be the optimal setup (i.e. upper mounted power supply with fan on the bottem of the power supply, lower mounted power supply with fan on the top of the power supply or vise versa)?
 
Thanks!

Depends. Some PSUs are designed to draw air in a 120mm fan on the top/bottom (depending what way you mount it) and expell it out the back, sometimes with the aid of a smaller fan. I personally have one like that and use it as another case fan, drawing warm air out of the case. While this mightn't be the best thing for the power supply, I haven't found anything that'd recommend against doing that.
 
If you're worried about it warming up things inside your case, or getting overheated itself depending on which way it's designed and mounted, get a case with set of vents for placing the PSU on the bottom at the rear, drawing air from outside the case (through a vent on the bottom) and blowing it out the back.

    It all depends on the PSU, if your PSU seams to be able to drawl air out of the case, then its best to be up top, so that it can exhaust air form the CPU/NB.  IF not then its best to have it on the bottom so that it wont get heated up by the warm air from the CPU/NB trying to get around the PSU.